The goal is to explore the role of water in biological function. Although water's role is considered secondary, recent evidence from this laboratory implies that its role may be more primary. Next to hydrophilic surfaces, water acquires special properties: it is charged, more ordered, and it excludes solutes. This interfacial zone is more extensive than previously thought, and it expands in the presence of radiant energy, particularly at infrared wavelengths. Because cells are crowded with hydrophilic surfaces and water, and because radiant energy is present as well, the above-mentioned features may be highly relevant for cell function. Up to now they have not been considered. The hypothesis is that they are unexpectedly crucial, and the goal is to test in a number of representative biological systems whether that is indeed the case. The mechanisms to be pursued include the following: (1) Diffusion and osmosis. Do the above-mentioned features play a central role? (2) Surface tension and oxygen exchange. Since these features are present at the air-water interface, do they govern oxygen exchange? (3) Self-assembly. The presence of ample near-surface charge in water leads to an explanation of why like-charged molecules can attract. Could this be a putative mechanism for self-assembly? (4) Light-induced effects. Incident light is known to be therapeutic. Do the aforementioned water-based features offer a possible explanation? (5) Vascular anomalies. The above-mentioned features lead to simple hypotheses for flow dynamics and atherosclerosis. Can these hypotheses be validated? (6) Global health. Because the interfacial zone excludes bacteria, purified water can be obtained. Can this approach be developed for global health applications? If the newly discovered features prove to be centrally relevant as hypothesized, then their relevance might extend more generally. If so, then this water-based approach may crack open the door to a new realm of biological understanding. PUBLIC HEALTH RELEVANCE: The proposed studies deal with the role of water in biological function. Water's role has been underestimated. The experiments will test for a more central role of water than has been previously estimated. If the proposed hypotheses are validated, then a fresh understanding of biomedical principles should result.